A known method of forming reinforced plastics articles is to lay a mat of non-woven or woven glass fibre or other reinforcement in a mould, to wet the mat of reinforcing material with a synthetic resin material, to cure the resin and to remove the moulded article from the mould. When a greater thickness of reinforced plastics material is required in the moulded article then further mats of reinforcing material are laid over the first, wetted and cured. This known method is not continuous, is slow, labour intensive and unsuitable for automation. Moreover, with mats of non-woven fibres the distribution of the fibres is random so that the strength characteristics of the reinforcement in any particular direction are unpredictable. With woven reinforcing materials the warp and weft are crimped where they intersect which reduces the strength thereof and makes it impossible to form the reinforcing material to complex shapes without creasing or buckling.
It is also known to mould reinforced plastics articles by mixing chopped reinforcing fibres in a synthetic resin material and moulding the resulting mixture in a closed mould. This method suffers from the disadvantage that the chopped reinforcing fibres are randomly distributed and randomly oriented in the finished article with the result that the article may contain resin-rich and reinforcing fibre-rich areas whereby the quality and mechanical properties of the article can be unpredictable.
Another known method of forming reinforced plastics articles is by pultrusion, wherein yarns or threads of reinforcing material are fed either alone or together with strips of woven or non-woven reinforcing material through a pultrusion die, the reinforcing material is wetted with a synthetic plastics material as it passes through the die and the synthetic plastics material is cured as the formed article emerges from the die. This method enables articles of complex cross-sectional shape to be produced but suffers from the disadvantage that the yarns or threads can become bunched together as they pass through the pultrusion die making it difficult to produce articles of consistent quality and strength.
A further known method of producing reinforced plastics articles, such as pipes and tubes, is by filament winding wherein reinforcing yarns or threads are wetted with synthetic resin material and are wound on a former to produce the article. The reinforcing yarns or threads are wound on the rotating former by traversing means which can be controlled to lay the reinforcing yarns or threads on the former at a required angle relative to the longitudinal axis of the former to provide required hoop strength in the finished article. It is not, however, possible to provide reinforcing yarns or threads extending longitudinally of the article to provide longitudinal strength. Accordingly, where longitudinal strength is required it is usual to supplement the wound yarns or threads with one or more layers of woven or non-woven reinforcing material wrapped around the former. Not only is this method slow but it is also difficult by this method to produce articles having satisfactory longitudinal strength.